detect file encoding with chardet before parsing the .py file

deptry/import_parser.py

@@ -3,6 +3,8 @@
 from pathlib import Path
 from typing import List, Union
 
+import chardet
+
 from deptry.notebook_import_extractor import NotebookImportExtractor
 
 RECURSION_TYPES = [ast.If, ast.Try, ast.ExceptHandler, ast.FunctionDef, ast.ClassDef]
@@ -45,7 +47,7 @@ def get_imported_modules_from_str(self, file_str: str) -> List[str]:
         return self._get_import_modules_from(import_nodes)
 
     def _get_imported_modules_from_py(self, path_to_py_file: Path) -> List[str]:
-        with open(path_to_py_file) as f:
+        with open(path_to_py_file, encoding=self._get_file_encoding(path_to_py_file)) as f:
             root = ast.parse(f.read(), path_to_py_file)  # type: ignore
         import_nodes = self._get_import_nodes_from(root)
         return self._get_import_modules_from(import_nodes)
@@ -102,3 +104,8 @@ def _filter_exceptions(modules: List[str]):
                 logging.debug(f"Found module {exception} to be imported, omitting from the list of modules.")
                 modules = [module for module in modules if not module == exception]
         return modules
+
+    @staticmethod
+    def _get_file_encoding(file_name: Union[str, Path]) -> str:
+        rawdata = open(file_name, "rb").read()
+        return chardet.detect(rawdata)["encoding"]

pyproject.toml

@@ -16,6 +16,7 @@ toml = "^0.10.2"
 isort = "^5.10.1"
 click = "^8.0.0"
 importlib-metadata = { version = "*", python = "<=3.7" }
+chardet = "^5.0.0"
 
 [tool.poetry.dev-dependencies]
 black = "^22.6.0"

tests/test_import_parser.py

@@ -83,3 +83,53 @@ def test_import_parser_ignores_setuptools(tmp_path):
             f.write("import setuptools\nimport foo")
         imported_modules = ImportParser().get_imported_modules_for_list_of_files(["file.py"])
         assert set(imported_modules) == set(["foo"])
+
+
+def test_import_parser_ignores_setuptools(tmp_path):
+
+    with run_within_dir(tmp_path):
+        with open("file1.py", "w", encoding="utf-8") as f:
+            f.write(
+                """#!/usr/bin/python
+# -*- encoding: utf-8 -*-
+import foo
+print('嘉大')
+"""
+            )
+        with open("file2.py", "w", encoding="iso-8859-15") as f:
+            f.write(
+                """
+#!/usr/bin/python
+# -*- encoding: iso-8859-15 -*-
+import foo
+print('Æ	Ç')
+"""
+            )
+        with open("file3.py", "w", encoding="utf-16") as f:
+            f.write(
+                """#!/usr/bin/python
+# -*- encoding: utf-16 -*-
+import foo
+print('嘉大')
+"""
+            )
+        with open("file4.py", "w", encoding="cp861") as f:
+            f.write(
+                """#!/usr/bin/python
+# -*- encoding: cp861 -*-
+import foo
+print('foo')
+"""
+            )
+
+        imported_modules = ImportParser().get_imported_modules_from_file(Path("file1.py"))
+        assert set(imported_modules) == set(["foo"])
+
+        imported_modules = ImportParser().get_imported_modules_from_file(Path("file2.py"))
+        assert set(imported_modules) == set(["foo"])
+
+        imported_modules = ImportParser().get_imported_modules_from_file(Path("file3.py"))
+        assert set(imported_modules) == set(["foo"])
+
+        imported_modules = ImportParser().get_imported_modules_from_file(Path("file4.py"))
+        assert set(imported_modules) == set(["foo"])